#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <vector>
// 1. 
struct ListNode {
    int val;
    ListNode* next;
    ListNode() : val(0), next(nullptr) {}
    ListNode(int x) : val(x), next(nullptr) {}
    ListNode(int x, ListNode* next) : val(x), next(next) {}
};

class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode* head = nullptr, * tail = nullptr;
        int carry = 0;
        while (l1 || l2)
        {
            int num1 = l1 ? l1->val : 0;
            int num2 = l2 ? l2->val : 0;
            int sum = num1 + num2 + carry;
            if (!head)
            {
                head = tail = new ListNode(sum % 10);
            }
            else
            {
                tail->next = new ListNode(sum % 10);
                tail = tail->next;
            }
            carry = sum / 10;
            if (l1)
            {
                l1 = l1->next;
            }
            if (l2)
            {
                l2 = l2->next;
            }
        }
        if (carry)
        {
            tail->next = new ListNode(carry);
            tail = tail->next;
        }
        return head;
    }
};

// 2. 
class Solution {
public:
    vector<int> singleNumber(vector<int>& nums) {
        int xorsum = 0;
        for (int num : nums)
        {
            xorsum ^= num;
        }
        int lsb = (xorsum & (-xorsum));
        int type1 = 0, type2 = 0;
        for (int num : nums)
        {
            if (num & lsb)
            {
                type1 ^= num;
            }
            else
            {
                type2 ^= num;
            }
        }

        return { type1,type2 };
    }
};